Use Two Button in Same web page

Question

  i am using two button in same page,example Sinup form in gmail  one button is used for submit ,another button used for Check the id is availble are not
i use some validation controls also like required field validator
When i Click check button that time validation control are show the error msg
 
i need when Submit button click then only work all the validation controls
                                                 Thank you
                                                                                          Student
                                                                                                 b.arul